The invention relates to a method for the pre-baking treatment of a chunk of frozen bread dough, which, in this specification, means unshaped dough with no particular form.
A chunk of frozen bread dough is usually taken out from a freezer or a refrigerated warehouse, and thawed out in a room(a room temperature method) or in a proofer (a thawing and proofing method). After the completion of thawing, dough with a temperature of between 0xc2x0 C.xcx9c20xc2x0 C. is put in a proofer for a final proofing process. The thawing may be finished in 1xcx9c3 hours in these methods. However, since the surface of the bread dough will be seriously dampened in these methods, a precaution has to be taken against the dampness, including the covering of the bread dough with a sheet of plastic film.
Recently, a thawing method using a retarder is adopted for relieving workers of their early morning shift, in which the thawing process is carried out for 6xcx9c24 hours at a temperature range of 0xc2x0 C.xcx9c5xc2x0 C. Further, a dough conditioner is used in which the retarder is equipped with a computer system, enabling a continuous and automated processes of thawing and final proofing.
Japanese Patent Publication Hei.6-36707 discloses a thawing method, comprising heating shaped and frozen bread dough for 2xcx9c6 hours up to a temperature of 10xc2x0 C. at an average temperature-raising rate of 0.07xcx9c0.28xc2x0 C./min and a relative humidity of 70xcx9c100%, and further keeping it for 10 minxcx9c6 hours at a temperature of 10xc2x0 C.xcx9c20xc2x0 C. and a relative humidity of 70xcx9c100%.
Japanese Patent Application Laid Open Hei.5-64539 discloses a bread-making method, comprising thawing with retardation frozen bread dough for 10 minxcx9c72 hours at a temperature of xe2x88x925xcx9c10xc2x0 C./min, a relative humidity of 90xcx9c100% and ventilation rate of 0.2 m/s or less, pre-heating it for one hour and 20 minxcx9c2 hours and 10 min up to a temperature of 15xcx9c20xc2x0 C., heating it for 20 minxcx9cone hours and 10 min up to a temperature of 22xcx9c40xc2x0 C., keeping it for 20 minxcx9c3 hours at the same temperature, and then baking the bread dough.
Japanese Patent Application Laid Open Hei.7-155100 discloses a method of keeping bread in a suitable condition for baking for a long period of time, comprising keeping the bread at a temperature of 0xcx9c18xc2x0 C. after final proofing in order to inhibit the activity of bakers"" yeast.
Japanese Patent No. 2729669 discloses a method for the pre-baking treatment of frozen bread dough comprising adjusting a thawing condition for each of different kinds of bread that need different time for their final proofing, so that their final proofing may be done simultaneously.
The purpose of the present invention is first to simplify complicated pre-baking work, secondly to standardize the pre-baking work of various kinds of bread dough in order to simultaneously carry out their pre-baking, and finally to increase baking frequency of bread dough.
By utilizing a chunk of frozen bread dough, it will be possible to simplify the work in a bakery and to significantly reduce the workload, when compared with a conventional scratch baking method wherein all the processes from mixing to baking are continuously in store. Without a specialized apparatus such as a mixer or proofer, and a professional baker or artisan having a specialized technique, it would be therefore possible to make bread with a small amount of investment and working space.
However, even if the chunk of frozen bread dough is used at a usual bakery where 60xcx9c100 kinds of bread are made, they can not be produced more than twice per day so that freshly baked bread can hardly be always provided to customers all the day.
The reasons for that may be as follows, for example: First, according to the conventional pre-baking treatment methods, the thawing and shaping processes have to be repeated for each baking process, and it is actually impossible to frequently repeat the processes; second, since each kind of bread items needs different time for their thawing and final proofing processes, an individual treatment will be required for each kind of bread. As a result, the number of working processes and working frequency will be increased and working processes will be more complicated as the number of the bread items are increased.
It is therefore desirable to simplify the working for bread making by continuously carrying out thawing and proofing processes, and keeping the proofed bread dough for a certain period of time so that the following final proofing and baking can be done at any optional time.
The present invention is related to a method for the pre-baking treatment of a chunk of frozen bread dough, comprising continuously carrying out a thawing process and a proofing process of the chunk of frozen bread dough in a container while keeping its inner temperature at a range of 17xcx9c40xc2x0 C., preferably of 22xcx9c35xc2x0 C. and its inner relative humidity at a range of 50xcx9c75%, preferably of 60xcx9c65%, and after the completion of the proofing, lowering its inner temperature to a range of xe2x80x9420xcx9c15xc2x0 C., preferably of 0xcx9c10xc2x0 C. at a lowering rate of 0.2xc2x0 C./min or more, preferably 0.4xc2x0 C./min or more while controlling the difference between a dew point in the container and a temperature on the bread surface within 20xc2x0 C. or less, preferably 15xc2x0 C. or less so that the condition of the bread dough may be maintained, followed by a shaping process and a final proofing process.
According to the present invention, it is possible to continuously carry out the thawing and proofing processes of the chunk of frozen bread dough by putting the bread dough in a container whose inner temperature and relative humidity have already been set at desired ranges without necessity of any further change of its temperature or relative humidity thereafter.
An xe2x80x9cinner relative humidityxe2x80x9d means that of air in the container and is an average value subjected to fluctuation at a range of about xc2x110%.
The time required for the thawing and proofing under the high temperature and low relative humidity in the present invention may be optionally determined by those skilled in the art, usually ranging from several tens minutes to about 10 hours, preferably from about 2 to 4 hours. The time required for the maintaining and proofing under the low temperature and high relative humidity in the present invention may be optionally determined by those skilled in the art, too, usually ranging from about 30 min to about 24 hours, preferably from about 2 to 6 hours.
If the bread dough is maintained at a higher temperature than said range for a long period of time, it will be over-proofed and cause disadvantages such as insufficiency in baking color and sweetness.
According to the present invention, the temperature or relative humidity in the container during the thawing and proofing processes is not necessarily kept at a constant level, either, as long as they are kept at the above ranges.
It is not necessary to keep the lowing rate of the temperature at a constant level, either, but may change gradually or continuously in the above range.
According to the present invention, bread dough with an excellent shaping-workability and an appropriate moistness will be produced in a container by thawing and proofing a chunk of frozen bread dough in the container under a high temperature and a low relative humidity, and maintaining the condition of the bread dough to continue the proofing under a low temperature and a high relative humidity for a certain period of time.
Further, any precautions to prevent the dampness on the surface of the bread dough, such as covering it with a sheet of plastic film, are not necessary, so that the workability and sanitation will be improved.
The maintenance of the bread dough under a proofing condition for several hours after the thawing and proofing in the present invention will produce a proofing taste and give a sufficient degree of proofing, resolving the problem of irregularity in thawing that was found in the prior methods. And the bread dough with a stable temperature may be given, which can also be finally proofed in a stable condition (the time for the final proofing) in the following final proofing process.
Further, according to the present invention, it is possible to rapidly inhibit the activity of bakers"" yeast in the bread by lowering the inner temperature to a range of xe2x88x9220xcx9c15xc2x0 C., preferably of 0xcx9c10xc2x0 C. at a lowering rate of 0.2xc2x0 C./min or more, preferably 0.4xc2x0 C./min or more.
As a result, it is possible to minimize the change in the condition of the bread, especially that in its volume, so that the bread dough may be maintained in an excellent condition.
And it is possible to obtain bread dough with an excellent shaping-workability and an appropriate moistness on its surface by controlling the difference between a dew point in the same container and a temperature on the bread surface within 20xc2x0 C. or less.
Alternatively, the continuous processes of thawing and proofing of the present invention may be carried out by raising its inner temperature to a range of 17xcx9c40xc2x0 C., preferably of 20xcx9c40xc2x0 C. at a raising rate of 0.1xcx9c2xc2x0xc2x0 C./min, preferably 0.3xcx9c1xc2x0 C./min and with its inner relative humidity at a range of 50xcx9c75%. It is possible to obtain bread dough with an excellent shaping-workability and an appropriate moistness on its surface, especially by keeping the difference between a dew point in the container and a temperature of the bread surface within 20xc2x0 C. or less, preferably within 15xc2x0 C. or less.
In the above case, it is not necessary to keep the container with its inner temperature at a range of 17xcx9c40xc2x0 C. at the time of putting the bread dough in it. Thus, the bread may be put and kept in the container with its inner temperature at a range of xe2x88x9220xcx9c15xc2x0 C. and its inner temperature may be raised later.
The raising rate is not necessarily kept at the same level during the raising period, but may be varied within the above range. Thus, the raising rate may change continuously or gradually. Further, after the temperature in the container has been raised to a certain level, it may be kept within the above range to continue the proofing process.
The difference between a dew point in the container and a temperature of the bread surface according to the present invention is an average value and subjected to fluctuation at a range of about xc2x110%.
The above difference may be determined by any method known to those skilled in the art. For example, the dew point of air may be obtained from a psychrometric chart that shows a relationship between a temperature and humidity, and the temperature on the bread surface may be actually measured by means of a known temperature sensor.
The present inventors also have found that the bread dough after the shaping process may be maintained under the same condition in a refrigerator for a certain period of time, for example for 30 minxcx9c5 hours, by keeping its inner temperature at a range of xe2x88x925xcx9c20xc2x0 C., preferably of xe2x88x925xcx9c5xc2x0 C. and its inner relative humidity at a range of 80xcx9c100%, followed by the final proofing and baking processes.
Thus, under the above condition, the activity of bakers"" yeast is so low that the bread dough will hardly swell, and the appropriate moistness on the surface of the bread dough may be kept during the long period of time.
As a result, it is possible according to the present invention to simultaneously carry out a complicated shaping process in the pre-baking treatment, allowing an optional shifting to the next final proofing process and baking process at any desired time.
Further, the bread dough after the final proofing process may be maintained under the same condition in a refrigerator for a certain period of time, for example for 30 minxcx9c5 hours, by keeping its inner temperature at a range of xe2x88x925xcx9c20xc2x0 C., preferably of xe2x88x925xcx9c5xc2x0 C. and its inner relative humidity at a range of 80xcx9c100%, followed by the baking process at an optional timing.
In this case, however, since the bread dough may further swell to some extent during the above maintaining period due to an increased activity of the bakers"" yeast after the final proofing, the final proofing should be finished in an earlier stage than usual.
According to the present invention, the above maintaining period may be provided both before and after the final proofing process.
An apparatus which may be used in the present invention for thawing, final proofing, and maintaining the bread dough under cooling after the final proofing process is generally called a xe2x80x9cdough conditioner,xe2x80x9d in which heating, cooling, humidifying, and dehumidifying may be optionally done. Especially, it is desirable to use a dough conditioner having a cooling power of more than 400 W, preferably more than 600 W and a heating power of more than 600 W, preferably more than 1 KW per 20 Kg of frozen bread dough. Any other type of dough conditioners known in the art may be used in the present invention.
There is no limitation with respect to materials used for the present chunk of frozen bread dough and their content ratios. For example, those skilled in the art may optionally select them depending on the kind of final products including sweetened buns such as bean-filled ones and butter roll.
Starting bread dough prepared by optionally mixing various materials may be subjected to well known processes such as pre-treatment, mixing, kneading, and proofing, then dividing, rounding, dry-proofing, and molding, followed by freezing by means of a freezer such as an xe2x80x9cair blast freezerxe2x80x9d and keeping in the freezer and the like at an appropriate temperature.
It is not necessary to keep the bread dough in a xe2x80x9cbench timexe2x80x9d in the method according to the present invention, but the bread dough may be shaped immediately after the thawing and proofing processes. The shaping process may be carried out by means of any conventional apparatus such as a molder.
The shape of the frozen bread dough may be optionally selected by those skilled in the art depending on the kind of the final products.